rAD pROTECTIONMinimizing patient exposure

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Which of the following projections is most likely to deliver the largest dose to the ovaries?

A

AP lumbar spine, 7 × 17 in. cassette, 80 kVp

B

AP lumbar spine, 14 × 17 in. cassette, 80 kVp

C

AP abdomen, 80 kVp

D

AP abdomen, 70 kVp

B

Which of the following will reduce patient dose during fluoroscopy?

1.

Decreasing the source-skin distance (SSD)

2.

Using 2.5 mm Al filtration

3.

Restricting tabletop intensity to less than 10 R/min

A

1 only

B

1 and 2 only

C

2 and 3 only

D

1, 2, and 3

C

Which of the following is (are) likely to improve image quality and decrease patient dose?

Beam restriction

Low kilovolt and high milliampere- second factors

Grids

A

1 only

B

1 and 3 only

C

2 and 3 only

D

1, 2, and 3

A

If a patient received 0.9 rad during a 3-minute fluoroscopic examination, what was the dose rate?

A

3 mrad/min

B

30 mrad/min

C

300 mrad/min

D

3,000 mrad/min

C

The interaction illustrated in Figure 3–5

can pose a safety hazard to personnel

can have a negative impact on image quality

occurs with low-energy incident photons

A

1 only

B

1 and 2 only

C

2 and 3 only

D

1, 2, and 3

B

Which of the following result(s) from restriction of the x-ray beam?

Less scattered radiation production

Less patient hazard

Less radiographic contrast

A

1 only

B

1 and 2 only

C

2 and 3 only

D

1, 2, and 3

B

Classify the following tissues in order of increasing radiosensitivity

Liver cells

Intestinal crypt cells

Muscle cells

A

1, 3, 2

B

2, 3, 1

C

2, 1, 3

D

3, 1, 2

D

Which one of the following is (are) used to control the production of scattered radiation?

Collimators

Optimal kV

Use of grids

A

1 only

B

1 and 2 only

C

2 and 3 only

D

1, 2, and 3

B

It is essential to question female patients of childbearing age regarding the

date of their last menstrual period

possibility of their being pregnant

number of x-ray examinations they have had in the past 12 months

A

1 only

B

1 and 2 only

C

1 and 3 only

D

1, 2, and 3

B

If the exposure rate to an individual standing 2.0 m from a source of radiation is 15 R/min, what will be the dose received after 2 minutes at a distance of 5 m from the source?

A

1.2 R

B

2.4 R

C

4.8 R

D

9.6 R

C

From which of the following primary beam sizes, all other factors remaining constant, will the greatest radiation exposure result?

A

8 × 10

B

10 × 12

C

11 × 14

D

14 × 17

d

Patient dose increases as fluoroscopic

A

FOV increases

B

FOV decreases

C

FSS increases

D

FSS decreases

B

If a patient received 2000 mrad during a 10-minute fluoroscopic examination, what was the dose rate?

A

0.2 rad/min

B

2.0 rad/min

C

5 rad/min

D

200 rad/min

A

Which of the following methods can be used to reduce radiation exposure to a recently fertilized ovum?

Elective booking

Patient questionnaire

The 10-day rule

A

1 only

B

1 and 2 only

C

2 and 3 only

D

1, 2, and 3

D

The interaction between x-ray photons and tissue that is responsible for radiographic contrast but that also contributes significantly to patient dose is

A

the photoelectric effect

B

Compton scatter

C

coherent scatter

D

pair production

A

What is the approximate entrance skin exposure (ESE) for the average anteroposterior (AP) supine abdomen radiograph?

A

300 rad

B

300 mrad

C

35 rad

D

35 mrad

B

A fluoroscopic examination requires 3 minutes of exposure on time. If the exposure rate for the examination is 250 mR/hr, what is the approximate exposure for the three minute procedure?

A

83.3 R

B

83.3 mR

C

12.5 R

D

12.5 mR

D

An increase of 1.0 mm added aluminum filtration of the x-ray beam would have which of the following effects?

Increase in average energy of the beam

Increase in patient skin dose

Increase in milliroentgen output

A

1 only

B

1 and 2 only

C

2 and 3 only

D

1, 2, and 3

A

For radiographic examinations of the skull, it is generally preferred that the skull be examined in the

A

AP projection

B

PA projection

C

recumbent position

D

supine position

B

PA projection

Which of the following most effectively minimizes radiation exposure to the patient?

A

Small focal spot

B

Low-ratio grids

C

Increased SID

D

High-speed intensifying screens

D

High-speed intensifying screens

he focal spot-to-table distance, in mobile fluoroscopy, must be

A

a minimum of 15 inches.

B

a maximum of 15 inches.

C

a minimum of 12 inches.

D

a maximum of 12 inches.

C

a minimum of 12 inches.

Filters used in radiographic x-ray tubes generally are composed of

A

aluminum

B

copper

C

tin

D

lead

A

aluminum

Which of the following terms is correctly used to describe x-ray beam quality?

A

mA

B

HVL

C

Intensity

D

Dose rate

B

HVL

Patient exposure can be minimized by using which of the following?

1.

Accurate positioning

2.

High-kV, low-mAs factors

3.

Rare earth screens

A

1 only

B

1 and 2 only

C

1 and 3 only

D

1, 2, and 3

D

1, 2, and 3

If a patient received 1,400 mrad during a 7-minute fluoroscopic examination, what was the dose rate?

A

200 rad/min

B

5 rad/min

C

2.0 rad/min

D

0.2 rad/min

D

All the following have an effect on patient dose except

A

kilovoltage

B

milliampere-seconds

C

focal spot size

D

inherent filtration

C

focal spot size

Patient dose during fluoroscopy is affected by the

distance between the patient and the input phosphor

amount of magnification

tissue density

A

1 only

B

3 only

C

2 and 3 only

D

1, 2, and 3

D

1, 2, and 3

Aluminum filtration has its greatest effect on

A

low-energy x-ray photons

B

high-energy x-ray photons

C

low-energy scattered photons

D

high-energy scattered photons

A

low-energy x-ray photons

Which of the following is (are) associated with Compton scattering?

1.

High-energy incident photons

2.

Outer-shell electrons

3.

Characteristic radiation

A

1 only

B

1 and 2 only

C

2 and 3 only

D

1, 2, and 3

B

1 and 2 only

Which of the following would be the safest interval of time for a fertile woman to undergo abdominal radiography without significant concern for irradiating a recently fertilized ovum?

A

The first 10 days following the cessation of menstruation

B

The first 10 days following the onset of menstruation

C

The 10 days preceding the onset of menstruation

D

About 14 days before menstruation

B

The first 10 days following the onset of menstruation

What is the approximate ESE for the average upright PA chest radiograph using 115 kVp and a grid?

A

20 rad

B

20 mrad

C

200 rad

D

200 mrad

B

20 mrad

The advantages of beam restriction include which of the following?

Less scattered radiation is produced.

Less biologic material is irradiated.

Less total filtration will be necessary.

A

1 only

B

1 and 2 only

C

2 and 3 only

D

1, 2, and 3

B

1 and 2 only

The SSD in mobile fluoroscopy must be

A

a minimum of 15 in.

B

a maximum of 15 in.

C

a minimum of 12 in.

D

a maximum of 12 in.

C

a minimum of 12 in.

Types of structural damage to a DNA molecule by ionizing radiation include which of the following?

single-side-rail scission

double-side-rail scission

cross-linking

A

1 only

B

2 only

C

1 and 2 only

D

1, 2, and 3

D

1, 2, and 3

Which of the following functions to protect the x-ray tube and the patient from overexposure in the event that the phototimer fails to terminate an exposure?

A

Circuit breaker

B

Fuse

C

Backup timer

D

Rheostat

C

Backup timer

Inherent and added filtration in the x-ray tube functions to

A

reduce patient skin dose.

B

shorten the scale of contrast.

C

reduce scattered radiation.

D

soften the x-ray beam.

A

reduce patient skin dose.

Which of the following would be most likely to cause the greatest skin dose (ESE)?

A

Short SID

B

High kilovoltage

C

Increased filtration

D

Increased milliamperage

A

Short SID

Which of the following groups of exposure factors would deliver the lowestpatient dose?

A

2.5 mAs, 100 kVp, 400-speed screens

B

10 mAs, 90 kVp, 200-speed screens

C

10 mAs, 70 kVp, 800-speed screens

D

10 mAs, 80 kVp, 400-speed screens

A

2.5 mAs, 100 kVp, 400-speed screens

When an image intensifier's magnification mode is used,

1.

output screen gain is increased.

2.

resolution increases.

3.

patient dose increases.

A

1 only

B

1 and 2 only

C

2 and 3 only

D

1, 2, and 3

C

2 and 3 only

What quantity of radiation exposure to the reproductive organs is required to cause temporary infertility?

A

100 rad

B

200 rad

C

300 rad

D

400 rad

B

200 rad

Which of the following groups of exposure factors will deliver the least patient dose?

A

300 mA, 250 ms, 70 kVp

B

300 mA, 125 ms, 80 kVp

C

400 mA, 90 ms, 80 kVp

D

600 mA, 30 ms, 90 kVp

D

600 mA, 30 ms, 90 kVp

The primary function of filtration is to reduce

A

patient skin dose

B

operator dose

C

image noise

D

scattered radiation

A

patient skin dose

If a patient received 2000 mrad during a 10-minute fluoroscopic examination, what was the dose rate?

A

0.02 rad/min

B

0.2 rad/min

C

2.0 rad/min

D

20 rad/min

B

0.2 rad/min

How many HVLs are required to reduce the intensity of a beam of monoenergetic photons to less than 15% of its original value?

A

2

B

3

C

4

D

5

B

3

How does filtration affect the primary beam?

A

It increases the average energy of the primary beam.

B

It decreases the average energy of the primary beam.

C

It makes the primary beam more penetrating.

D

It increases the intensity of the primary beam.

A

It increases the average energy of the primary beam.

It is necessary to question a female patient of childbearing age regarding her

date of last menstrual period

possibility of being pregnant

age at her first pregnancy

A

1 only

B

1 and 2 only

C

1 and 3 only

D

2 and 3 only

B

1 and 2 only

Which of the following will increase patient dose during fluoroscopy?

Decreasing the SSD

Using 2.5 mm Al filtration

Restricting tabletop intensity to less than 10 R/min

A

1 only

B

1 and 2 only

C

2 and 3 only

D

1, 2, and 3

A

1 only

Which of the following is most likely to result in the greatest increase in patient exposure?

A

Changing from a 400 speed system to a 200 speed system

B

Increasing kVp 15% and cutting mAs in half

C

Using two tomographic cuts instead of two plain images

D

From nongrid technique to 8:1 grid

D

From nongrid technique to 8:1 grid

Which of the following groups of exposure factors will deliver the leastamount of exposure to the patient?

A

400 mA, 0.25 second, 100 kVp

B

600 mA, 0.33 second, 90 kVp

C

800 mA, 0.5 second, 80 kVp

D

800 mA, 1.0 second, 70 kVp

A

400 mA, 0.25 second, 100 kVp

The measure of the rate at which energy is transferred from ionizing radiation to soft tissue is termed

A

the characteristic effect

B

Compton scatter

C

linear energy transfer

D

the photoelectric effect

C

linear energy transfer

The most efficient type of male gonadal shielding for use during fluoroscopy is

A

flat contact

B

shaped contact (contour)

C

shadow

D

cylindrical

B

shaped contact (contour)

A test radiograph like the one pictured in Figure A would be made by the radiation safety officer (RSO) or equipment service person and is used to evaluateFigure A. Courtesy of Stamford Hospital, Department of Radiology

A

focal spot size.

B

linearity.

C

collimator alignment.

D

spatial resolution.

C

collimator alignment.

What is the approximate entrance skin exposure (ESE) for the average AP supine lumbar spine radiograph?

A

350 rad

B

350 mrad

C

35 rad

D

35 mrad

B

350 mrad

With milliamperes (mA) increased to maintain output intensity, how is the ESE affected as the source-to-skin distance (SSD) is increased?

A

The ESE increases.

B

The ESE decreases.

C

The ESE remains unchanged.

D

ESE is unrelated to SSD.

B

The ESE decreases.

Which of the following is most likely to permit the greatest decrease in patient exposure?

A

Changing from a 200-speed system to a 400-speed system

B

Increasing kilovoltage by 15% and cutting the milliampere-seconds value in half

C

Changing collimation from 10 × 12 to 14 × 17

D

Changing from an 8:1 grid technique to nongrid

D

Changing from an 8:1 grid technique to nongrid

Moving the image intensifier closer to the patient during traditional fluoroscopy

decreases the SID

decreases patient dose

improves image quality

A

1 only

B

1 and 2 only

C

1 and 3 only

D

1, 2, and 3

D

1, 2, and 3

Radiation safety requirements for fluoroscopic equipment include the following:

1.

SSD at least 38 cm on stationary (fixed) equipment.

2.

SSD at least 30 cm on mobile equipment.

3.

high level/boost mode must have continuous audible signal.

A

1 only

B

1 and 2 only

C

2 and 3 only

D

1, 2, and 3

D

1, 2, and 3

If the exposure rate to an individual standing 4.0 m from a source of radiation is 10 mR/h, what will be the dose received after 20 minutes at a distance of 6 m from the source?

A

22.5 mR

B

7.5 mR

C

4.44 mR

D

1.48 mR

D

1.48 mR

When the collimated field must extend past the edge of the body, allowing primary radiation to strike the tabletop, as in a lateral lumbar spine radiograph, what may be done to prevent excessive radiographic density owing to undercutting?

A

Reduce the milliampere-seconds.

B

Reduce the kilovoltage.

C

Use a shorter SID.

D

Use lead rubber to absorb tabletop primary radiation.

D

Use lead rubber to absorb tabletop primary radiation.

Which of the following is (are) important for patient protection during fluoroscopic procedures?

1.

Intermittent fluoroscopy

2.

Fluoroscopic field size

3.

Focus-to-table distance

A

1 and 2 only

B

1 and 3 only

C

2 and 3 only

D

1, 2, and 3

D

1, 2, and 3

A minimum total amount of aluminum filtration (inherent plus added) of 2.5 mm is required in equipment operated

A

above 50 kVp

B

above 60 kVp

C

above 70 kVp

D

above 80 kVp

C

above 70 kVp

The primary function of filtration is to reduce

A

patient skin dose.

B

operator dose.

C

image noise.

D

scattered radiation.

A

patient skin dose.

Which of the following safeguards is (are) taken to prevent inadvertent irradiation in early pregnancy?